Reactions of alkenes Flashcards
Why are alkenes more reactive?
Alkenes are more reactive than alkanes because of the C=C double bond.
Where is the sigma bond in alkanes?
In an alkane, the single bond between carbon atoms is a sigma bond.
In an alkene, what is the double bond?
In an alkene, the double bond between two carbons is made of a sigma bond and a pi bond.
What happens when a C=C splits?
A pi bond is weaker than a sigma bond. When an alkene reacts the pi bonds break and the sigma bond remains intact.
What happens in addition reactions?
Alkenes typically take part in addition reactions – small molecules added across the double bond causing the pi bonds to be broken, two reactants form one products, an unsaturated alkene reacts forming a saturated product.
What happens in the addition of Hydrogen?
Hydrogen gas/gaseous alkenes passed over a nickel catalyst at 150 C. Hydrogen adds across double bond/alkane formed. Hydrogenation, type of reduction.
What happens in the addition of Halogens?
Halogen adds across double bond to give a di-substituted halogenoalkane – sometimes known as halogenation.
What happens when an alkane is added to bromine?
Bromine + Alkane have a colour change from orange to colourless.
